Approval sheet
WK12M / WK08M / WK06M
0/-20% and 0/-30%
Trimmable chip resistors
Size 1206, 0805, 0603
*Contents in this sheet are subject to change without prior notice.
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ASC_WKxxM_V01
Dec.2010
Approval sheet
FEATURE
1. Reduced size of final equipment
2. Lower assembly costs
3. Higher component and equipment reliability
4. Improved performance at high frequency
5. Low noise, when not trimmed
6. RoHS compliant and Lead free termination
APPLICATION
•
•
•
•
Consumer electrical equipment
Automotive application
EDP, Computer application
Telecom application
DESCRIPTION
The resistors are constructed on a high-grade ceramic body (aluminum oxide). Internal metal electrodes are
added at each and connected by a resistive paste, which is applied to the substrate. The composition of the
paste is adjusted to give the approximate resistance required.
The resistive layer is covered with a transparent protective coating. Finally the two external end terminations are
added. For case of soldering the outer of theses end terminations is a Tin (lead free) alloy.
Fig 1. Consctruction of Trimmable Chip-R
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ASC_WKxxM_V01
Dec.2010
Approval sheet
QUICK REFERENCE DATA
Item
Series No.
Size code
Resistance Range
Tolerance
TCR (ppm/°C)
≥10Ω
<10Ω
Max. dissipation at T
amb
=70°C
Max. Operation Voltage (DC or RMS)
Climatic category (IEC 60068)
Note :
1.
2.
This is the maximum voltage that may be continuously supplied to the resistor element, see “IEC publication
60115-8”
Max. Operation Voltage : So called RCWV (Rated Continuous Working Voltage) is determined by
≤ ±
200 ppm/°C
-200~+500 ppm/°C
1/8 W
200V
≤ ±
200 ppm/°C
-200~+500 ppm/°C
1/10W
150V
55/125/56
1/16W
50V
≤ ±
200 ppm/°C
WK12M
1206 (3216)
1Ω ~ 4.7MΩ
General Specification
WK08M
0805 (2012)
1Ω ~ 4.7MΩ
0/-20% and 0/-30% (E24 series)
WK06M
0603 (1608)
10Ω ~ 4.7MΩ
RCWV
=
Rated Power
×
Resistance Value
or Max. RCWV listed above, whichever is lower.
DIMENSIONS(unit: mm)
WK12M
L
W
T
Tb
Tt
3.10
±
0.15
1.60
±
0.15
0.55
±
0.10
0.50
±
0.25
0.50
±
0.25
WK08M
L
W
T
Tb
Tt
2.00
±
0.10
1.25
±
0.10
0.55
±
0.10
0.40
±
0.20
0.40
±
0.20
WK06M
1.60
±
0.10
0.80
±
0.10
0.45
±
0.10
0.30
±
0.10
0.30
±
0.10
MARKING
No marking for Trimmable Chip Resistor
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ASC_WKxxM_V01
Dec.2010
Approval sheet
TRIMMING INTRODUCTIONS
Typical value for a YAG-laser;
cutting speed
laser power
bite size
: 10-200 mm/sec,
: 1-6 Watt,
: 3~10µm ( = speed / Q_rate , Bite Size is the distance each laser spot moving and
influence the trimming accuracy)
maximum trimming length : 60% of resistive film width, minimum distance from end termination to trimming
cut : 0.20mm, minimum distance between cuts (double-cut) : 0.5mm
Protection of the laser cut
by epoxy-fenol lacquers, epoxy resins or silicon alkyd-resins.
This is necessary for humidity test and stability under loaded.
FUNCTIONAL DESCRIPTION
Product characterization
Standard values of nominal resistance are taken from the E24 series for resistors with a tolerance of 0/-20%,
and 0/-30%. The values of the E24 series are in accordance with “IEC publication 60063”
Derating
The power that the resistor can dissipate depends on the operating temperature; see Fig.2
Figure 2
Maximum dissipation in percentage of rated power
as a function of the ambient temperature
MOUNTING
Due to their rectangular shapes and small tolerances, Surface Mountable Resistors are suitable for handling by
automatic placement systems.
Chip placement can be on ceramic substrates and printed-circuit boards (PCBs).
Electrical connection to the circuit is by individual soldering condition.
The end terminations guarantee a reliable contact.
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ASC_WKxxM_V01
Dec.2010
Approval sheet
SOLDERING CONDITION
The robust construction of chip resistors
allows them to be completely immersed in a
solder bath of 260°C for 10 seconds.
Therefore, it is possible to mount Surface
Mount Resistors on one side of a PCB and
other discrete components on the reverse
(mixed PCBs).
Surface Mount Resistors are tested for
solderability at 235°C during 2 seconds. The
test condition for no leaching is 260°C for 30
seconds. Typical examples of soldering
processes that provide reliable joints without
any damage are given in Fig 3.
Fig 3. Infrared soldering profile for Chip Resistors
CATALOGUE NUMBERS
The resistors have a catalogue number starting with :
WK12
Size code
WK12
WK08
WK06
: 1206
: 0805
: 0603
Type code
M : Trimmable
M
472_
Resistance code
E24 : 2 significant digits
followed by no. of
zeros and a blank
4.7Ω
10Ω
220Ω
=4R7_
=100_
=221_
X
Tolerance
X : 0/-30%
Y : 0/-20%
T
Packaging code
T
B
: 7” Reeled taping
: Bulk
L
Termination code
L
=
Sn base (lead
free)
(“_” means a blank)
1.
Reeled tape packaging : WK12M / WK08M / WK06M - 8mm width paper taping 5000pcs per reel.
Bulk packaging
: WK12M / WK08M / WK06M - 5000pcs per poly bag
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ASC_WKxxM_V01
Dec.2010
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